EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 92 (1): 333-340, 1995

Biological activity and receptor-binding of ecdysteroids and the ecdysteroid agonists RH-5849 and RH-5992 in imaginal wing discs of Spodoptera exigua (Lepidoptera: Noctuidae)

SMAGGHE G., DEGHEELE D.

N/A

The effects of 20-hydroxyecdysone (20E), ponasterone A (PoA) and both dibenzoylhydrazine-based ecdysteroid agonists RH-5849 and RH-5992, were tested on in vitro-cultured imaginal wing discs of last-instar larvae of the beet armyworm, Spodoptera exigua (Hübner). In each case, the response was qualitatively similar to that induced by 20E, although the concentrations required to induce response varied widely. The EC₅₀ of both ecdysteroids 20E and PoA to elicit wing disc evagination in 50% of the discs was 89.8 and 2.57 nM, respectively; for both nonsteroid agonists RH-5849 and RH-5992 this was 870 and 11.7 nM, respectively. Binding competition studies using whole imaginal wing discs, showed that I₅₀ of 20E, PoA, RH-5849 and RH-5992 to displace 50% of [³H]PoA-binding was 290, 7, 1100 and 33 nM, respectively, which is in the same order as the respective concentration to elicit a biological response.

Keywords: Ecdysone, nuclear hormone receptor, imaginal discs, Lepidoptera, ecsdysteroid assay

Accepted: January 3, 1995; Published: February 24, 1995  Show citation